Ultra-high efficiency turbine and fuel cell combination

ABSTRACT

A turbine power system that includes a compressor for compressing a first medium, and an electrochemical converter in communication with the compressor and adapted to receive the first medium and a second medium. The converter is configured to allow an electrochemical reaction between the first and second mediums, thereby generating electricity and producing exhaust having a selected elevated temperature. The power system further includes a turbine in fluid communication with the electrochemical converter and adapted to receive the converter exhaust, such that the turbine converts the electrochemical converter exhaust into rotary energy and electricity. The system can further include a steam generator and a steam turbine that produces electricity. The electrochemical converter is utilized herein as an electrochemical combustor-replacement (ECCR) or as a fuel cell for combustor-replacement (FCCR).

RELATED APPLICATIONS

This application is a continuation-in-part application of applicationSer. No. 287,093, entitled "Electrochemical Converter Having InternalThermal Integration", filed 8 Aug. 1994, now U.S. Pat. No. 5,501,781,which is herein incorporated by reference. This application is alsorelated to the copending application Ser. No. 08/215,466, entitled"Electrochemical Converter Having Optimal Pressure Distribution", filedon 21 Mar. 1994, now abandoned, which is herein incorporated byreference.

BACKGROUND OF THE INVENTION

This invention relates to gas or steam turbines, and specifically tohigh performance power systems employing such devices.

Conventional high performance gas turbine power systems exist and areknown. Prior gas turbine power systems include a compressor, acombustor, and a mechanical turbine, typically connected in-line, e.g.,connected along the same axis. In a conventional gas turbine, air entersthe compressor and exits at a desirable elevated pressure. Thishigh-pressure air stream enters the combustor, where it reacts withfuel, and is heated to a selected elevated temperature. This heated gasstream then enters the gas turbine and expands adiabatically, therebyperforming work. One deficiency of gas turbines of this general type isthat the turbine typically operates at relatively low systemefficiencies, for example, around 25%, with systems of megawattcapacity.

One prior art method employed to overcome this problem is to employ arecuperator for recovering heat. This recovered heat is typically usedto further heat the air stream prior to the stream entering thecombustor. Typically, the recuperator improves the system efficiency ofthe gas turbine upwards to about 30%. A drawback of this solution isthat the recuperator is relatively expensive and thus greatly adds tothe overall cost of the power system.

Another prior art method employed is to operate the system at arelatively high pressure and a relatively high temperature to therebyincrease system efficiency. However, the actual increase in systemefficiency has been nominal, while the system is subjected to the costsassociated with the high temperature and pressure mechanical components.

Still another prior art method utilized by plants having powercapacities above 100 MW is to thermally couple the high temperatureexhaust of the turbine with a heat recovery steam generator for acombined gas turbine/steam turbine application. This combined cycleapplication typically improves the system operating efficiency upwardsto about 55%. However, this efficiency is still relatively low.

Thus, there exists a need in the art for high performance power systems.In particular, an improved gas turbine power system that is capable ofintegrating and employing the desirable properties of electrochemicalconverters would represent a major improvement in the industry. Moreparticularly, an integrated electrochemical converter and gas turbinesystem that reduces the costs associated with providing dedicatedthermal processing systems while significantly increasing the overallsystem power efficiency would also represent a major improvement in theart.

SUMMARY OF THE INVENTION

The present invention provides for a power system that integrates anelectrochemical converter with a gas turbine. The electrochemicalconverter and gas turbine constitute a relatively highly efficient powersystem, e.g., efficiency about 70%, for the production of electricity.

The gas turbine power system of the present invention includes acompressor for compressing a first medium, and an electrochemicalconverter in fluid communication with the compressor and adapted toreceive the first medium and a second medium. The converter isconfigured to allow an electrochemical reaction between the first andsecond mediums, thereby producing exhaust having a selected elevatedtemperature. The power system further includes a turbine in fluidcommunication with the electrochemical converter and adapted to receivethe converter exhaust, such that the turbine converts theelectrochemical converter exhaust into rotary energy.

According to one aspect of the invention, the power system furtherincludes a generator which receives the rotary energy of the turbine,and which produces electricity in response to the turbine rotary energy.The electrochemical converter is preferably adapted to operate at anelevated temperature and at various pressures.

According to another aspect, the power system further includes a heatexchanger element, in thermal association with the electrochemicalconverter, for extracting waste heat from the converter exhaust and fortransferring the waste heat to the turbine.

According to still another aspect, the electrochemical converterincludes an internal heating element that internally heats the first andsecond medium to the converter operating temperature. The converter iscomposed of, in another aspect, a plurality of tubular converterelements which include a circular electrolyte layer having an oxidizerelectrode material on one side and a fuel electrode material on theopposing side.

According to another aspect, the electrochemical converter includes anelectrochemical converter assembly having a plurality of stackedconverter elements which include a plurality of electrolyte plateshaving an oxidizer electrode material on one side and a fuel electrodematerial on the opposing side, and a plurality of interconnector platesfor providing electrical contact with the electrolyte plates, such thatthe stack of converter elements is assembled by alternately stackinginterconnector plates with the electrolyte plate. In another aspect, thestacked converter elements further include a plurality of manifoldsaxially associated with the stack and adapted to receive the first andsecond mediums, and a medium heating element, associated with themanifolds, for heating at least a portion of the first and secondmediums to the converter operating temperature.

According to yet another aspect, the interconnector plate is a thermallyconductive connector plate, and the medium heating element includes athermally conductive and integrally formed extended surface, integrallyformed with the interconnector plate, and which protrudes into the axialmanifolds. In another embodiment, the stack of converter elementsincludes a plurality of spacer plates interposed between the electrolyteplates and the interconnector plates, and the medium heating elementincludes a thermally conductive and integrally formed extended surfaceof the spacer plate that protrudes into the plurality of axialmanifolds.

According to one practice of the invention, the electrochemicalconverter assembly generates waste heat which heats the first and secondmediums to the converter operating temperature, and which isconductively transferred to the first and second mediums by theinterconnector plate.

According to another aspect, the power system further includes apreheating element for preheating the first and second mediums prior tointroduction to the electrochemical converter. The preheating element ispreferably either an external regenerative heat exchanger or a radiativeheat exchanger. According to another practice of the invention, eitherthe medium heating element or the preheating element can be utilized todisassociate the first and second mediums, which includes hydrocarbonsand reforming agents, into non-complex reaction species.

According to another aspect of the invention, the power system furtherincludes a converter exhaust heating element, in communication with theelectrochemical converter and the turbine, for heating the exhaust ofthe converter to a selected elevated temperature prior to introductionto the turbine. The exhaust heating element is preferably a natural gascombustor. The power system can further include a regenerative thermalenclosure element which forms a pressure vessel about theelectrochemical converter.

The invention further provides for a steam turbine power system thatincludes an electrochemical converter for producing exhaust and wasteheat having a selected elevated temperature, a steam generatorassociated with the electrochemical converter, and a turbine associatedwith the steam generator and configured for producing electricity.

According to one aspect, the steam turbine power system includes a heatexchanger element for radiatively exchanging heat between the converterand the steam generator.

According to another aspect, the power system further includes a heatrecovery heat exchanger, associated with the turbine, that receives theconverter exhaust and convectively transfers waste heat from theconverter exhaust to the turbine.

According to another aspect, the electrochemical converter includes anelectrochemical converter assembly having a plurality of stackedconverter elements which include a plurality of electrolyte plateshaving an oxidizer electrode material on one side and a fuel electrodematerial on the opposing side, and a plurality of interconnector platesfor providing electrical contact with the electrolyte plates. The stackof converter elements is assembled by alternately stackinginterconnector plates with the electrolyte plate.

According to another aspect, the stacked converter elements furtherincludes a plurality of manifolds axially associated with the stack andadapted to receive reactants, and a reactant heating element, associatedwith the manifolds, for heating at least a portion of the reactants tothe converter operating temperature.

According to still another aspect, the interconnector plate includes athermally conductive connector plate, and the reactant heating elementincludes a thermally conductive and integrally formed extended surfaceof the interconnector plate that protrudes into the plurality of axialmanifolds.

In yet another aspect, the stack of converter elements further includesa plurality of spacer plates interposed between the electrolyte platesand the interconnector plates.

According to another aspect, the reactant heating element includes athermally conductive and integrally formed extended surface of thespacer plate that protrudes into the plurality of axial manifolds.

According to one practice of the invention, the electrochemicalconverter assembly generates waste heat which heats the reactants to theconverter operating temperature. This waste heat is conductivelytransferred to the reactants by the interconnector plate.

In another aspect, the steam turbine power system further includes apreheating element for preheating the reactants prior to introduction tothe electrochemical converter. The preheating element can include anexternal regenerative heat exchanger or a radiative heat exchanger.

According to another practice, either or both the preheating element orthe reactant heating element disassociates the reactants, which includeshydrocarbons and reforming agents, into non-complex reaction species.

The invention further provides for a power system that includes anelectrochemical converter adapted to receive input reactants and toproduce waste heat and exhaust, and a gas turbine that includes acompressor and a mechanical turbine that produces exhaust having aselected elevated temperature. The system further includes a steamgenerator that receives the gas turbine exhaust and that radiativelycouples the exhaust of the gas turbine to a working medium. The systemalso includes a steam turbine that is associated with at least the steamgenerator and that is adapted to receive the working medium.

The invention further provides for a power system that includes anelectrochemical converter adapted to receive input reactants and toproduce waste heat and exhaust, and a gas turbine that includes acompressor and a mechanical turbine that produces exhaust having aselected elevated temperature. The system further includes a steamgenerator that receives the gas turbine exhaust and that convectivelycouples the exhaust of the gas turbine to a working medium. The systemalso includes a steam turbine that is associated with the steamgenerator and that is adapted to receive the working medium. Accordingto one practice, power is generated by the electrochemical converter,the steam turbine, and the gas turbine.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description and apparentfrom the accompanying drawings, in which like reference characters referto the same parts throughout the different views. The drawingsillustrate principles of the invention and, although not to scale, showrelative dimensions.

FIG. 1 is a schematic block diagram of a power system employing anelectrochemical converter serially in-line with a gas turbine accordingto the present invention;

FIG. 2 is a schematic block diagram of an alternate embodiment of apower system employing an electrochemical converter out of line with agas turbine according to the present invention;

FIG. 3 is a schematic block diagram of a power system employing anelectrochemical converter and a steam turbine according to the presentinvention;

FIG. 4 is a schematic block diagram of another embodiment of a powersystem employing both a gas turbine, a steam turbine, and a converterexhaust heating element according to the present invention;

FIG. 5 is a plan view, partially cut-away, of a pressure vesselenclosing a series of electrochemical converters of the presentinvention;

FIG. 6 is a perspective view of a basic cell unit of an electrochemicalconverter of the invention;

FIG. 7 is a perspective view of an alternate embodiment of the basiccell unit of the electrochemical converter of the present invention; and

FIG. 8 is a cross-sectional view of the cell unit of FIG. 6.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 shows a gas turbine power system according to the presentinvention. The illustrated in-line, aero-derivative gas turbine powersystem 70 includes an electrochemical converter 72 and a gas turbineassembly. The gas turbine comprises a compressor 76, a turbine 80, and agenerator 84. Air from air source 73 is introduced to the compressor 76by way of any suitable conduit where it is compressed, and thus heated,and then discharged and introduced to the electrochemical converter 72.The fuel 74 is introduced to a preheater 68 where it is preheated to aselected elevated temperature below the converter operating temperature.The heated air and fuel function as input reactants and power theelectrochemical converter 72.

The converter 72 heats the compressed air introduced by the compressor76 and the fuel 74 to produce high temperature exhaust. The exhaust isintroduced to the gas turbine 80, which converts this thermal energyinto rotary energy, for subsequent transfer to an electric generator 84.The generator 84 produces electricity that can be used for bothcommercial and residential purposes. One benefit of utilizing theelectrochemical converter as the gas turbine combustor is that theconverter functions as an additional electric generator. The illustratedelectrical connections 88A and 88B show that electricity can beextracted from both the generator 84 and the converter 72. The gasturbine components and generator are art known and commerciallyavailable. Those of ordinary skill will readily understand theintegration of the electrochemical converter and the gas turbine,especially in light of the present description and illustrations.

FIG. 2 illustrates a power system 90 where the electrochemical converter72' is coupled off-line from the gas turbine. Air from the air source73' is compressed by the compressor 76', discharged, and then introducedto the off-line converter 72'. Fuel from a fuel source 74' is introducedto the converter and the air and fuel are consumed thereby. Theconverter thermally disassociates the fuel into constituent non-complexreaction species, typically H₂ and CO, and creates high temperatureexhaust. The exhaust is introduced to the gas turbine 80' which iscoupled to the electric generator 84'. The illustrated generator 84' andconverter 72' can be used to power the illustrated propulsion motor 86.The system 90 can further employ a preheater, similar to the preheaterof FIG. 1, to preheat the reactants prior to introduction to theconverter 72.

FIG. 3 illustrates a power system 95 that employs an electrochemicalconverter 72", a heat recovery steam generator 108 (HRSG), and a steamturbine 112, connected as shown. The steam generator 108 functions as apreheater by preheating the input reactants, e.g., air and fuel, to adesirable elevated temperature below the operating temperature of theconverter 72'. The converter utilizes the input reactants and createswaste heat and heated exhaust 91. The exhaust 91 can be conveyed to thesteam generator 108 by any suitable means, such as a conduit. The heatedexhaust helps preheat the reactants 73,74 by a regenerative heatexchange process, while concomitantly heating working medium associatedwith the steam turbine, such as water, to produce steam for the steamturbine 112. In an alternate embodiment, the steam generator 108includes internally a reformer for reforming fuel by thermaldisassociation, which typically involves the reformation of hydrocarbonsand reforming agents into non-complex reaction species.

FIG. 4 shows an alternate power system 100 that utilizes anelectrochemical converter, a gas turbine, and a steam turbine. The powersystem 100 includes, in addition to the above-listed system components,a secondary combustor 104, a steam generator 108, and a steam turbine112'. Fuel from a fuel source 74 and water 102 for reforming, generallysupplied by a fluid reservoir (not shown), are introduced to theelectrochemical converter 72". The water 102 and the waste heat producedby the converter 72" help reform the input fuel, e.g., fossil fuel, intousable non-complex reaction species, e.g., molecular hydrogen and carbonmonoxide. Air from the air source 73 is preferably introduced to theconverter 72" by way of the compressor or blower 76" and combines withthe input fuel to power the converter 72". The converter 72" produces ahigh temperature exhaust, typically around 1000° C., which is furtherheated to a selected elevated temperature, e.g., 1300° C., by thesecondary combustor 104 to match the predetermined inlet temperaturerequirements of the gas turbine 80". The gas turbine produces an exhaustoutput 81 which is passed through a heat recovery steam generator 108for subsequent use with the bottoming steam turbine 112. The steamturbine output is coupled to the electric generator 84" which produceselectricity. Electrical connections 88A' and 88B' indicate thatelectricity can be directly extracted from both the electrochemicalconverter 72" and the generator 84".

The illustrated power systems of FIGS. 1-4 provide the advantage in thatthey allow electricity to be produced in an high efficiency system bythe direct integration of a high efficiency, compact electrochemicalconverter with the bottoming plant constituent components. Theintegration of the electrochemical converter with a gas turbine in themanner illustrated in FIGS. 1-4 produces a gas turbine power system thathas an overall power efficiency of about 70%. This system efficiencyrepresents a significant increase over the efficiencies achieved byprior art gas turbine systems and prior art electrochemical systems. Theillustrated gas turbine power systems incorporate an electrochemicalconverter to provide high grade thermal energy and electricity, whileutilizing the benefits of electrochemical converters. For example, theconverter operates as a low NOx thermal source, thereby improvingenvironmental performance relative to conventional gas turbinegenerating plants.

The direct integration of an electrochemical converter with a gasturbine is aided when the electrochemical converter 72 is housed withina high pressure vessel 120. A preferred type of converter encasement isillustrated in FIG. 5, where a pressure vessel 120, which also functionsas a regenerative thermal enclosure, encases a series of stacked fuelcell assemblies 122, which are described in greater detail below. Thepressure vessel 120 includes an exhaust outlet manifold 124, electricalconnectors 126 and input reactant manifolds 128 and 130. In a preferredembodiment, the oxidizer reactant is introduced to the resident fuelcell assemblies through the centrally located manifolds 130, and thefuel reactant is introduced through the fuel manifolds 128 located aboutthe periphery of the vessel 120.

As described above, the electrochemical converter can be operated at anelevated temperature and at either ambient pressure or at an elevatedpressure. The electrochemical converter is preferably a fuel cell systemthat can include an interdigitated heat exchanger, similar to the typeshown and described in U.S. Pat. No. 4,853,100, which is hereinincorporated by reference.

Fuel cells typically disassociate fuel by utilizing the chemicalpotential of selected fuel species, such as hydrogen or carbon monoxidemolecules, to produce oxidized molecules in addition to electricalpower. Since the cost of supplying molecular hydrogen or carbon monoxideis relatively higher than providing traditional fossil fuels, a fuelprocessing or reforming step can be utilized to convert the fossilfuels, such as coal and natural gas, to a reactant gas mixture high inhydrogen and carbon monoxide. Consequently, a fuel processor, eitherdedicated or disposed internally within the fuel cell, is employed toreform, by the use of steam, oxygen, or carbon dioxide (in anendothermic reaction), the fossil fuels into non-complex reactant gases.

FIGS. 6-8 illustrate the basic cell unit 10 of the electrochemicalconverter 72, which is particularly suitable for integration withconventional gas turbines. The cell unit 10 includes an electrolyteplate 20 and an interconnector plate 30. In one embodiment, theelectrolyte plate 20 can be made of a ceramic, such as a stabilizedzirconia material ZrO₂ (Y₂ O₃), on which a porous oxidizer electrodematerial 20A and a porous fuel electrode material 20B are disposedthereon. Exemplary materials for the oxidizer electrode material areperovskite materials, such as LaMnO₃ (Sr). Exemplary materials for thefuel electrode material are cermets such as ZrO₂ /Ni and ZrO₂ /NiO.

The interconnector plate 30 preferably is made of an electrically andthermally conductive interconnect material. Examples of such materialinclude nickel alloys, platinum alloys, non-metal conductors such assilicon carbide, La(Mn)CrO₃, and preferably commercially availableInconel, manufactured by Inco., U.S.A. The interconnector plate 30serves as the electric connector between adjacent electrolyte plates andas a partition between the fuel and oxidizer reactants. As best shown inFIG. 8, the interconnector plate 30 has a central aperture 32 and a setof intermediate, concentric radially outwardly spaced apertures 34. Athird outer set of apertures 36 are disposed along the outer cylindricalportion or periphery of the plate 30.

The interconnector plate 30 has a textured surface 38. The texturedsurface preferably has formed thereon a series of dimples 40, as shownin FIG. 8, which form a series of connecting reactant-flow passageways.Preferably, both sides of the interconnector plate 30 have the dimpledsurface formed thereon. Although the intermediate and outer set ofapertures 34 and 36, respectively, are shown with a selected number ofapertures, those of ordinary skill will recognize that any number ofapertures or distribution patterns can be employed, depending upon thesystem and reactant-flow requirements.

Likewise, the electrolyte plate 20 has a central aperture 22, and a setof intermediate and outer apertures 24 and 26 that are formed atlocations complementary to the apertures 32, 34 and 36, respectively, ofthe interconnector plate 30.

Referring to FIG. 7, a spacer plate 50 can be interposed between theelectrolyte plate 20 and the interconnector plate 30. The spacer plate50 preferably has a corrugated surface 52 that forms a series ofconnecting reactant-flow passageways, similar to the interconnectingplate 30. The spacer plate 50 also has a number of concentric apertures54, 56, and 58 that are at locations complementary to the apertures ofthe interconnect and electrolyte plates, as shown. Further, in thisarrangement, the interconnector plate 30 is devoid of reactant-flowpassageways. The spacer plate 50 is preferably made of an electricallyconductive material, such as nickel.

The illustrated electrolyte plates 20, interconnector plates 30, andspacer plates 50 can have any desirable geometric configuration.Furthermore, the plates having the illustrated manifolds can extendoutwardly in repetitive or non-repetitive patterns, and thus are shownin dashed lines.

Referring to FIG. 8, when the electrolyte plates 20 and theinterconnector plates 30 are alternately stacked and aligned along theirrespective apertures, the apertures form axial (with respect to thestack) manifolds that feed the cell unit with the input reactants andthat exhaust spent fuel. In particular, the aligned central apertures22,32,22' form input oxidizer manifold 17, the aligned concentricapertures 24,34,24' form input fuel manifold 18, and the aligned outerapertures 26,36,26' form spent fuel manifold 19.

The dimpled surface 38 of the interconnector plate 30 has, in thecross-sectional view of FIG. 8, a substantially corrugated patternformed on both sides. This corrugated pattern forms the reactant-flowpassageways that channel the input reactants towards the periphery ofthe interconnector plates. The interconnector plate also has an extendedheating surface or lip structure that extends within each axial manifoldand about the periphery of the interconnector plate. Specifically, theinterconnector plate 30 has a flat annular extended surface 31A formedalong its outer peripheral edge. In a preferred embodiment, theillustrated heating surface 31A extends beyond the outer peripheral edgeof the electrolyte plate 20. The interconnector plate further has anextended heating surface that extends within the axial manifolds, forexample, edge 31B extends into and is housed within the axial manifold19; edge 31C extends into and is housed within the axial manifold 18;and edge 31D extends into and is housed within the axial manifold 17.The extended heating surfaces can be integrally formed with theinterconnector plate or can be coupled or attached thereto. The heatingsurface need not be made of the same material as the interconnectorplate, but can comprise any suitable thermally conductive material thatis capable of withstanding the operating temperature of theelectrochemical converter. In an alternate embodiment, the extendedheating surface can be integrally formed with or coupled to the spacerplate.

The absence of a ridge or other raised structure at the interconnectorplate periphery provides for exhaust ports that communicate with theexternal environment. The reactant-flow passageways connect, fluidwise,the input reactant manifolds with the outer periphery, thus allowing thereactants to be exhausted to the external environment, or to a thermalcontainer or pressure vessel disposed about the electrochemicalconverter, FIG. 5.

Referring again to FIG. 8, the illustrated sealer material 60 can beapplied to portions of the interconnector plate 30 at the manifoldjunctions, thus allowing selectively a particular input reactant to flowacross the interconnector surface and across the mating surface of theelectrolyte plate 20. The interconnector plate bottom 30B contacts thefuel electrode coating 20B of the electrolyte plate 20. In thisarrangement, it is desirable that the sealer material only allow fuelreactant to enter the reactant-flow passageway, and thus contact thefuel electrode.

As illustrated, the sealer material 60A is disposed about the inputoxidizer manifold 17, forming an effective reactant flow barrier aboutthe oxidizer manifold 17. The sealer material helps maintain theintegrity of the fuel reactant contacting the fuel electrode side 20B ofthe electrolyte plate 20, as well as maintain the integrity of the spentfuel exhausted through the spent fuel manifold 19.

The top 30A of the interconnector plate 30 has the sealer material 60Bdisposed about the fuel input manifolds 18 and the spent fuel manifold19. The top of the interconnector plate 30A contacts the oxidizercoating 20B' of an opposing electrolyte plate 20'. Consequently, thejunction at the input oxidizer manifold 17 is devoid of sealer material,thereby allowing the oxidizer reactant to enter the reactant-flowpassageways. The sealer material 60B that completely surrounds the fuelmanifolds 18 inhibits the excessive leakage of the fuel reactant intothe reactant-flow passageways, thus inhibiting the mixture of the fueland oxidizer reactants. Similarly, the sealer material 60C thatcompletely surrounds the spent fuel manifold 19 inhibits the flow ofspent oxidizer reactant into the spent fuel manifold 19. Hence, thepurity of the spent fuel that is pumped through the manifold 19 ismaintained.

Referring again to FIG. 8, the oxidizer reactant can be introduced tothe electrochemical converter through axial manifold 17 that is formedby the apertures 22, 32, and 22' of the electrolyte and interconnectorplates, respectively. The oxidizer is distributed over the top of theinterconnector plate 30A, and over the oxidizer electrode surface 20A'by the reactant-flow passageways. The spent oxidizer then flows radiallyoutward toward the peripheral edge 31A, and is finally discharged alongthe converter element periphery. The sealer material 60C inhibits theflow of oxidizer into the spent fuel manifold 19. The flow path of theoxidizer through the axial manifolds is depicted by solid black arrows26A, and through the oxidizer cell unit by the solid black arrows 26B.

The fuel reactant is introduced to the electrochemical converter 10 byway of fuel manifold 18 formed by the aligned apertures 24, 34, and 24'of the plates. The fuel is introduced to the reactant-flow passagewaysand is distributed over the bottom of the interconnector plate 30B, andover the fuel electrode coating 20B of the electrolyte plate 20.Concomitantly, the sealer material 60A, prevents the input oxidizerreactant from entering the reactant-flow passageways and thus mixingwith the pure fuel/spent fuel reactant mixture. The absence of anysealer material at the spent fuel manifold 19 allows spent fuel to enterthe manifold 19. The fuel is subsequently discharged along the annularedge 31A of the interconnector plate 30. The flow path of the fuelreactant is illustrated by the solid black arrows 26C.

The dimples 40 of the interconnector surface have an apex 40A thatcontact the electrolyte plates, in assembly, to establish an electricalconnection therebetween.

A wide variety of conductive materials can be used for the thinelectroconnector plates of this invention. Such materials should meetthe following requirements: (1) high strength, as well as electrical andthermal conductivity; (2) good oxidation resistance up to the workingtemperature; (3) chemical compatibility and stability with the inputreactants; and (4) manufacturing economy when formed into the texturedplate configuration exemplified by reactant-flow passageways.

The suitable materials for interconnector fabrication include nickelalloys, nickel-chromium alloys, nickel-chromium-iron alloys,iron-chromium-aluminum alloys, platinum alloys, cermets of such alloysand refractory material such as zirconia or alumina, silicon carbide andmolybdenum disilicide.

The textured patterns of the top and bottom of the interconnector platecan be obtained, for example, by stamping the metallic alloy sheets withone or more sets of matched male and female dies. The dies arepreferably prefabricated according to the desired configuration of theinterconnector plate, and can be hardened by heat treatment to withstandthe repetitive compressing actions and mass productions, as well as thehigh operating temperatures. The stamp forming process for theinterconnectors is preferably conducted in multiple steps due to thegeometrical complexity of the gas passage networks, e.g., the dimpledinterconnector plate surface. The manifolds formed in the interconnectorplates are preferably punched out at the final step. Temperatureannealing is recommended between the consecutive steps to prevent theoverstressing of sheet material. The stamping method is capable ofproducing articles of varied and complex geometry while maintaininguniform material thickness.

Alternatively, corrugated interconnectors can be formed byelectro-deposition on an initially flat metal plate using a set ofsuitable masks. Silicon carbide interconnector plates can be formed byvapor deposition onto pre-shaped substrates, by sintering of bondedpowders, or by self-bonding processes.

The oxidizer and fuel reactants are preferably preheated to a suitabletemperature prior to entering the electrochemical converter. Thispreheating can be performed by any suitable heating structure, such as aregenerative heat exchanger or a radiative heat exchanger, for heatingthe reactants to a temperature sufficient to reduce the amount ofthermal stress applied to the converter.

Another significant feature of the present invention is that theextended heating surfaces 31D and 31C heat the reactants containedwithin the oxidizer and fuel manifolds 17 and 18 to the operatingtemperature of the converter. Specifically, the extended surface 31Dthat protrudes into the oxidizer manifold 17 heats the oxidizerreactant, and the extended surface 31C that protrudes into the fuelmanifold 18 heats the fuel reactant. The highly thermally conductiveinterconnector plate 30 facilitates heating of the input reactants byconductively transferring heat from the fuel cell internal surface,e.g., the middle region of the conductive interconnector plate, to theextended surfaces or lip portions, thus heating the input reactants tothe operating temperature prior to traveling through reactant flowpassageways. The extended surfaces thus function as a heat fin. Thisreactant heating structure provides a compact converter that is capableof being integrated with an electricity generating power system, andfurther provides a highly efficient system that is relatively low incost. Electrochemical converters incorporating fuel cell componentsconstructed according to these principles and employed in conjunctionwith a gas turbine provides a power system having a relatively simplesystem configuration.

The operating temperature of the electrochemical converter is preferablybetween about 20° C. and 1500° C., and the preferred fuel cell typesemployed by the present invention are solid oxide fuel cells, moltencarbonate fuel cells, alkaline fuel cells, phosphoric acid fuel cells,and proton membrane fuel cells.

In an alternate embodiment, the electrolyte and interconnector platescan have a substantially tubular shape and have an oxidizer electrodematerial disposed on one side and a fuel electrode material disposed onthe opposing side. The plates can then be stacked together in a likemanner.

It will thus be seen that the invention contains improvements over theprior art. Since certain changes may be made in the above constructionswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawings be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are to cover allgeneric and specific features of the invention described herein, and allstatements of the scope of the invention which, as a matter of language,might be said to fall therebetween. For example, the electrochemicalconverter employing the interconnector plate edge extensions of thepresent invention can also employ molten carbonate, phosphoric acid,alkaline and proton exchange membrane electrochemical converters andother like converters.

What is claimed is:
 1. A gas turbine power system for producingelectricity, comprisinga compressor for compressing a first medium, anelectrochemical converter in fluid communication with the compressor andbeing adapted to receive the first medium and a second medium, theconverter being configured to allow electrochemical reaction between thefirst and second mediums and to produce exhaust which is a combinationof the first and second mediums having a selected elevated temperature,and a turbine in fluid communication with the electrochemical converterand adapted to receive directly the converter exhaust, wherein theturbine converts the electrochemical converter exhaust into rotaryenergy.
 2. The gas turbine power system of claim 1 further comprising agenerator associated with the turbine and adapted to receive the rotaryenergy thereof, wherein the generator produces electricity in responseto the turbine rotary energy.
 3. The gas turbine power system of claim 1wherein the electrochemical converter is adapted to produce electricity.4. The gas turbine power system of claim 1 wherein the electrochemicalconverter is adapted to operate at an elevated temperature and atatmospheric pressure, and wherein said power system further comprisesheat exchanger means in thermal association with the electrochemicalconverter for extracting waste heat from the converter exhaust and fortransferring the waste heat to the turbine.
 5. The gas turbine powersystem of claim 1 wherein the electrochemical converter has a selectedoperating temperature and is adapted to operate at an elevatedtemperature and at an elevated pressure, wherein the electrochemicalconverter includes internal medium heating means for internally heatingthe first and second mediums to the converter operating temperature. 6.The gas turbine power system of claim 5 wherein the electrochemicalconverter comprises a plurality of tubular converter elements whichinclude a circular electrolyte layer having an oxidizer electrodematerial on one side and a fuel electrode material on the opposing side.7. The gas turbine power system of claim 1 wherein the electrochemicalconverter comprisesan electrochemical converter assembly having aplurality of stacked converter elements which includea plurality ofelectrolyte plates having an oxidizer electrode material on one side anda fuel electrode material on the opposing side, and a plurality ofinterconnector plates for providing electrical contact with theelectrolyte plates, wherein the stack of converter elements is assembledby alternately stacking interconnector plates with the electrolyteplate.
 8. The gas turbine power system of claim 7 wherein the stackedconverter elements further includea plurality of manifolds axiallyassociated with the stack and adapted to receive the first and secondmediums, and medium heating means associated with the manifold forheating at least a portion of the first and second mediums to theoperating temperature of the converter.
 9. The gas turbine power systemof claim 8 wherein the interconnector plate comprises a thermallyconductive connector plate.
 10. The gas turbine power system of claim 8wherein the medium heating means comprises a thermally conductive andintegrally formed extended surface of the interconnector plate thatprotrudes into the axial manifolds.
 11. The gas turbine power system ofclaim 8 wherein the stack of converter elements further comprises aplurality of spacer plates interposed between the electrolyte plates andthe interconnector plates.
 12. The gas turbine power system of claim 11wherein the medium heating means comprises a thermally conductive andintegrally formed extended surface of the spacer plate that protrudesinto the plurality of axial manifolds.
 13. The gas turbine power systemof claim 8 wherein the electrochemical converter assembly generateswaste heat which heats the first and second mediums to the converteroperating temperature, the waste heat being conductively transferred tothe first and second mediums by the interconnector plate.
 14. The gasturbine power system of claim 8 wherein at least the medium heatingmeans is adapted to dissociate the first and second mediums, whichincludes hydrocarbons and reforming agents, into non-complex reactionspecies.
 15. The gas turbine power system of claim 1 wherein means isprovided for maintaining the operating temperature of theelectrochemical converter assembly is between about 20° C. and about1500° C.
 16. The gas turbine power system of claim 1 wherein saidelectrochemical converter is a fuel cell selected from the groupconsisting of a solid oxide fuel cell, molten carbonate fuel cell,phosphoric acid fuel cell, alkaline fuel cell, and proton exchangemembrane fuel cell.
 17. The gas turbine power system of claim 1 furthercomprising preheating means for preheating the first and second mediumsprior to introduction to the electrochemical converter.
 18. The gasturbine power system of claim 17 wherein the preheating means comprisesone of an external regenerative heat exchanger and a radiative heatexchanger.
 19. The gas turbine power system of claim 17 wherein at leastthe preheating means is adapted to dissociate the first and secondmediums, which includes hydrocarbons and reforming agents, intonon-complex reaction species.
 20. The gas turbine power system of claim1 wherein the electrochemical converter is placed serially in-linebetween the compressor and the turbine.
 21. The gas turbine power systemof claim 1 further comprising converter exhaust heating means, disposedbetween the electrochemical converter and the turbine, for heating theexhaust of the converter to a selected elevated temperature prior tointroduction to the turbine.
 22. The gas turbine power system of claim21 wherein the converter exhaust heating means comprises a natural gascombustor.
 23. The gas turbine power system of claim 1 furthercomprising regenerative thermal enclosure means forming a pressurevessel about the electrochemical converter.
 24. The gas turbine powersystem of claim 1 further comprising means for introducing the firstmedium which includes air and means for introducing the second mediumwhich includes natural gas.
 25. The gas turbine power system of claim 1further comprising a steam generator associated with the gas turbine andadapted to receive the gas turbine exhaust, the steam generatorconvectively coupling the exhaust of the gas turbine to a workingmedium.
 26. The gas turbine power system of claim 25 further comprisinga steam turbine associated with the steam generator and configured forproducing electricity.
 27. A power generating system comprisinganelectrochemical converter assembly having a plurality of stackedconverter elements and being adapted to receive one or more reactants,and a gas turbine having a compressor and being associated with theelectrochemical converter, the compressor being adapted to preheat thereactants.
 28. The power generating system of claim 27 furthercomprising a generator associated with the gas turbine, wherein theturbine produces rotary energy and the generator produces electricity inresponse to the turbine rotary energy.
 29. A power system comprisinganelectrochemical converter adapted to receive input reactants and toproduce electricity, waste heat and exhaust, a gas turbine comprising acompressor and a mechanical turbine, the turbine producing electricityand exhaust having a selected elevated temperature, a steam generatorassociated with the gas turbine and adapted to receive the gas turbineexhaust, the steam generator convectively coupling the exhaust of thegas turbine to a working medium, and a steam turbine associated with thesteam generator and configured for producing electricity.
 30. The powersystem of claim 29 further comprising heating means associated with theelectrochemical converter and the gas turbine for heating the exhaust ofthe converter to a selected elevated temperature prior to introductionto the gas turbine.
 31. The power system of claim 30 wherein the heatingmeans is a natural gas combustor.